The RTV-A-2 Hiroc was a product of the United States' first effort to develop an intercontinental ballistic missile (ICBM). The project was named MX-774. The project was canceled in 1947, but leftover funds were used to build and launch three of the planned 10 research vehicles designated RTV-A-2. The design included several innovations; the gimbaled thrust chambers provided guidance control, the internal gas pressure was used to support the airframe and the nose cap was separable. All of these concepts were later used on the Atlas missile and the first two on the Viking rocket. Also developed as part of MX-774 was the Azusa guidance system which was not used on the Hiroc missile but did contribute to the Atlas missile as well as many other early guided missiles launched from Cape Canveral.

Reaction Motors, Inc. (RMI) was an early American maker of liquid-fueled rocket engines, located in New Jersey. RMI engines with 6,000 lbf (27 kN) thrust powered the Bell X-1 rocket aircraft that first broke the sound barrier in 1947, and later aircraft such the X-1A, X-1E, and the Douglas D-558-2 Skyrocket. A 20,000 lbf (89 kN) thrust RMI engine also powered the Viking research rocket, the first large liquid-fueled US high-altitude rocket. RMI was merged with Thiokol in 1958, where it produced the XLR-99 engine that powered the X-15 rocket aircraft.